In mobile radio communication networks, such as cellular telephone systems, neighboring radio cells provide coverage of a geographical area to be serviced. Each cell has a base station (BS) operating on a set of radio channels over which mobile subscribers communicate. A mobile switching center (MSC) controls calls between a group of base stations and various networks, e.g., the public switched telephone network (PSTN), integrated services digital network (ISDN), and one or more public land mobile radio networks (PLMN). The MSC performs functions such as call switching, routing, and charging.
All mobile communication networks provide the "basic call services" required for making and receiving calls in home and in foreign (hereinafter referred to as "visiting") mobile communication networks. In fact, known cellular systems like the Nordic Mobile Telephone System (NMT), the Total Access Communication System (TACS), the American Digital Cellular System (ADC), the Global System for Mobile Communication (GSM), and the Pacific Digital Cellular System (PDC) have adopted standardized techniques for providing such basic services. Basic services include calls to/from individual mobile subscribers and other services available to all mobile subscribers that do not require an individual service subscription.
In the fixed telephony network, intelligent networks (IN) were developed to provide additional, more flexible services to supplement existing telephony services. More recently, IN-based services have also become necessary and/or desirable in mobile telecommunications networks to provide supplementary services. Supplementary mobile services generally require an individual subscription and example supplementary services are call waiting, call forwarding, and call barring. Supplementary subscriber services may be divided into two types: (1) those which modify or supplement the process of "originating" a call, and (2) those which modify or supplement the process of "terminating" a call. Examples of originating supplementary services include: barring of outgoing calls and closed user group. Examples of terminating supplementary services include: barring incoming calls, call forwarding, and call waiting.
In the example of a GSM mobile communications system, (adopted for purposes of explanation and not limitation), efforts have been made to develop Intelligent Network (IN) capabilities for mobile network operators in the Customized Applications for Mobile Network Enhanced Logic (CAMEL) standard published by the European Telecommunications Standards Institute (ETSI) as GSM Technical Specification 03.78. The goal of the CAMEL standardization process is to provide mobile network operators with the capability to quickly design and offer new and enhanced mobile network-specific services using intelligent network type tools, e.g., service logic building blocks, service databases, service "trigger" or "detection" points, etc. For example, a service control point (SCP) node stores and implements service logic invoked to provide supplementary services. A service switching point (SSP) node handles service detection and switching functions necessary to invoke services at the SCP. However, to reconcile the mobility of the subscribers in this IN framework, functions performed by the HLR, the SCP, and the MSC must be coordinated.
In order to provide IN-based, network-specific services to mobile subscribers, network-specific service subscription information, (referred to in the GSM CAMEL example as CAMEL Subscription Information (CSI)), must be stored in the subscriber record for each mobile subscriber. In CAMEL, such services to be invoked at the origination of a call from a mobile subscriber are indicated with originating-CSI (O-CSI), and CAMEL services to be invoked for a terminating call to a mobile subscriber are indicated with terminating-CSI (T-CSI).
When a mobile subscriber leaves its home mobile communication network and registers at a visiting mobile communications network, that mobile subscriber's O-CSI must be sent from the HLR to the visiting mobile communications network as part of the typical mobile subscriber location update procedure. The O-CSI is stored at the visiting location register (VLR) database serving the area in which the mobile subscriber is currently located. Thereafter, when that mobile subscriber initiates or forwards a call, the visiting network MSC/VLR detects the O-CSI stored for that subscriber in the VLR. In effect, the O-CSI functions as a Detection Point (similar to an IN "trigger" point in fixed telephony networks) in the call processing which causes a transfer of control to the Service Control Point (SCP). The T-CSI also functions as a detection point in the call processing for incoming calls to the mobile station.
The present invention is directed to a supplementary service referred to in this application as an Advice of Charge (AoC) service. The AoC supplementary service notifies mobile telephone subscribers of the charge for a prospective originating or terminating call before the charges have occurred. In addition, the Advise of Charge service may also notify the mobile subscriber of total or accumulated charges for an ongoing call.
In the example GSM system, "E-parameters" may be used as AoC parameters from which the prospective costs and accumulated costs of a call can be calculated within the mobile terminal. Calculation of AoC parameters may be accomplished by performing tariff/charging analysis in each mobile switching node, e.g., the mobile switching center (MSC). However, there are problems with this approach. First, mobile switching nodes like MSCs generally do not perform tariff and charging analyses. But if all MSCs were programmed to perform charging and tariff analysis operations, this would add a significant administrative burden both for the MSCs and for the mobile network operators. Each mobile network operator would be required to provide charging and tariff information to all of the MSC nodes within the home network for each mobile subscriber. Moreover, the mobile network operator would have to update continuously in each MSC the charging and tariffing functions and parameters whenever they changed for each mobile station, e.g., mobile subscribers are added or deleted, mobile subscribers change their subscriptions, new discount pricing structures for various time periods, etc. Further, in order to be effective over a wide, inter-network coverage area, each MSC would require an enormous database to track charging for all mobile stations within its home network as well as all roaming mobile stations that might visit that network.
Another problem with this approach concerns a roaming mobile subscriber currently being served in a visiting network by a visiting MSC where the roaming mobile subscriber is to receive a call. In this instance, it is impossible for the visiting MSC currently serving the roaming mobile to calculate the total cost of the incoming call. Only the home mobile network operator has all of the billing information required to determine how much all portions of and services for the call will cost. For example, the visiting MSC will not know the cost(s) associated with the roaming leg of the call. Without an accurate total cost or projected cost of a call to a roaming mobile, the visiting MSCs cannot provide an AoC service. While it might be possible in theory for operators to exchange charging/billing information for all mobile subscribers, such an exchange would create an enormous administrative burden requiring huge databases and database updates.
It is an object of the present invention to overcome these difficulties and problems.
It is an object of the present invention to provide an Advice of Charge service to mobile subscribers for both mobile originating and mobile terminating calls.
It is a further object of the present invention to provide such Advice of Charge services efficiently to mobile subscribers located in their home mobile network as well as when they are roaming in visiting mobile networks without burdening mobile switching centers with administrative tasks associated with charging.
The present invention employs a central control point that administers an Advice of Charge (AoC) service provided to mobile subscribers. The control point is informed of each call involving a mobile that subscribes to the Advice of Charge service. The control point determines one or more AoC parameters for the call and sends them to the switching node currently serving the mobile subscriber. The mobile station receives the AoC parameters from the serving switching node and determines a prospective cost associated with the call and displays that cost to the mobile subscriber. Accumulated costs for that call may also be determined and displayed during the call.
Accordingly, the central control point performs the charging analysis for the mobile subscriber to determine the AoC parameters rather than a serving Mobile Switching Center (MSC). In a GSM example implementation, when a call is originated from the mobile, the MSC determines whether the mobile subscriber has a service controlled by a central control point, and if so, informs the control point of the call as well as its identity as the serving MSC. The control point then sends the AoC parameters for the call to the serving MSC, and the MSC forwards those parameters to the mobile.
In the opposite direction, when a call terminates at the mobile, the call is initially processed at a Gateway Mobile Switching Center (GMSC). Based on information from a home location register (HLR) database, the GMSC determines the mobile subscriber service and identifies the MSC currently serving that mobile subscriber. The GMSC informs the control point of the identity of the mobile subscriber and the serving MSC. The control point sends the determined AoC parameters to the serving MSC which forwards them to the mobile subscriber.
During a call, there may be a change in charging condition. If that is the case, the control point then determines new Advice of Charge parameters to account for the change in charging condition and sends those new AoC parameters to the mobile. The mobile then recalculates and displays the cost of the call to the mobile subscriber.
A preferred but nevertheless example embodiment of the present invention is disclosed in the context of a GSM mobile communications system which implements the Advice of Charge supplementary service using CAMEL/IN functionalities. A Service Switching Functionality (SSF) incorporated into the MSCs and GMSCs is used to detect when an Advice of Charge service should be invoked for a particular call. The Advice of Charge service is then administered under the control of a Service Control Point (SCP).